The United States doesn't make it any further west than the midwest very often. Most of the matches that the U.S. plays are on the east coast, especially the northeast, with the occasional match in the midwest and the American soccer fans on the west coast are well aware of this. They want to see their national team play without having to fly three hours. Lucky for them, they just might soon.
Travel usually keeps the U.S. from going too far west. Los Angeles gets matches and CONCACAF will play Gold Cup matches on the west coast upon occasion, but it is very rare that the U.S. Soccer Federation sends the national team to the Rockies or further. The reasoning is that it would be tough on the players who play for European club teams to fly all the way to the west coast and then back in the middle of the season. They did that in September for a friendly and the team paid for it with lethargic play that could have been a result of jetlag.
The October 16 Guatemala World Cup qualifier could give the U.S. the opportunity to go west, though. If the U.S. takes care of business in their first five matches of World Cup qualifying then they will have already qualified for the hexagonal stage by the time they play Guatemala and won't have to call in many European players. With a largely domestic squad, the west coast is an option. The U.S. had already qualified for the hexagonal by the time they got to the final match of the semifinal stage in 2010 World Cup qualifying and played the match in Colorado so there is history.
Steve Goff tweeted that the USSF will announce the host of that match by June 1 and went on to speculate that Salt Lake City, Denver or Portland could be an option. What do they have in common? They are on the west coast, or at least further west than the U.S. normally goes.
Portland and Seattle are at a disadvantage because they have turf and the U.S. has been unwilling to play qualifiers on turf or grass laid over turf in the past so Salt Lake City and Denver seem more likely. The U.S. could also go to the San Francisco/Bay Area then or even Texas, which hasn't had a U.S. match in a while and has brand new BBVA Compass Stadium in Houston. Options!